Dendritic Cells Supply CD4+ T Cells With L-arginine

Tuberculosis (TB), caused by Mycobacterium tuberculosis, is responsible for over 1 million deaths each year. Mycobacteria-infected dendritic cells (DCs) migrate to the lymph node to initiate adaptive immune priming, which is vital to antimycobacterial immunity. This response is intimately tied to nutrient availability – especially the amino acid L-arginine (L-ARG), metabolism of which is altered in TB patients. We have characterized a pathway utilized by immune cells to synthesize L-ARG. Loss of L-ARG synthesis in CD11c+ cells, which includes DCs, results in increased mycobacterial burden following infection in mice. To characterize the role of this pathway in DCs, we developed a co-culture system with mycobacterial-specific CD4+ T cells and bone marrow derived DCs. Using CD4+ T cells and DCs with differing capabilities of L-ARG synthesis, we found 1) DC L-ARG synthesis supports CD4+ T cell proliferation and 2) activated T cells contain DC-derived L-ARG. We hypothesize DCs “share” synthesized L-ARG to support CD4+ T cell activation when L-ARG is limiting. Our data suggest nutrient availability as a 4th signal – following antigen presentation, co-stimulation, and cytokine receptor ligation – required for T cell activation. This work expands the current model of DC-T cell interactions and provides insight into the effects of nutrient availability in immune cells.

Unraveling the Relationship Between Itching, Scratch Scales, and Biomarkers in Children With Alagille Syndrome

Pruritus is a debilitating symptom for patients with Alagille syndrome (ALGS). In a previously reported trial of maralixibat, an investigational antipruritic agent, itching was assessed using a digital diary based on twice‐daily caregiver observation of itching severity (Itch Reported Outcome, ItchRO[Observer]). The goal of this study was to characterize pruritus in participants with ALGS at baseline in this trial, as assessed by the ItchRO instrument and the physician‐observed clinician scratch scale (CSS), relative to biomarkers putatively associated with pruritus and health‐related quality of life assessment. Thirty‐seven participants with ALGS (median age of 6 years; range 1‐17 years) were enrolled. No association was identified between CSS and ItchRO(Obs) (r = 0.22, P = 0.2). Neither CSS nor ItchRO were associated with serum bile acids (r = −0.08, P = 0.6 for both) or autotaxin (r = 0.22, P = 0.2; r = 0.28, P = 0.12). There was no significant association between Pediatric Quality of Life Inventory total parent scores and CSS or ItchRO (r = −0.23, P = 0.2; r = −0.16, P = 0.36). There was a significant association between ItchRO and Multidimensional Fatigue Scale and Family Impact Module total scores (Pearson correlation coefficient −0.575, P = 0.0005; 0.504, P = 0.002). In exploratory analysis, selected questions relating to fatigue and sleep disturbance (n = 12) from Pediatric Quality of Life Inventory, Multidimensional Fatigue Scale, and Family Impact Module were correlated with pruritus scores; positive associations were identified. Conclusion: Itching scores did not correlate with each other, nor with putative serum biomarkers of pruritus, and further, did not correlate with quality of life. Hypothesis‐generating analyses implicate sleep disturbance and fatigue as key associations with caregiver observations of itching. This is highly relevant to the selection of surrogate endpoints for clinical trials of pruritus therapies.

The FOXM1 Inhibitor RCM-1 Decreases Carcinogenesis and Nuclear β-Catenin

The oncogenic transcription factor FOXM1 has been previously shown to play a critical role in carcinogenesis by inducing cellular proliferation in multiple cancer types. A small-molecule compound, Robert Costa Memorial drug-1 (RCM-1), has been recently identified from high-throughput screen as an inhibitor of FOXM1 in vitro and in mouse model of allergen-mediated lung inflammation. In the present study, we examined antitumor activities of RCM-1 using tumor models. Treatment with RCM-1 inhibited tumor cell proliferation as evidenced by increased cell-cycle duration. Confocal imaging of RCM-1-treated tumor cells indicated that delay in cellular proliferation was concordant with inhibition of FOXM1 nuclear localization in these cells. RCM-1 reduced the formation and growth of tumor cell colonies in the colony formation assay. In animal models, RCM-1 treatment inhibited growth of mouse rhabdomyosarcoma Rd76-9, melanoma B16-F10, and human H2122 lung adenocarcinoma. RCM-1 decreased FOXM1 protein in the tumors, reduced tumor cell proliferation, and increased tumor cell apoptosis. RCM-1 decreased protein levels and nuclear localization of β-catenin, and inhibited protein-protein interaction between β-catenin and FOXM1 in cultured tumor cells and in vivo Altogether, our study provides important evidence of antitumor potential of the small-molecule compound RCM-1, suggesting that RCM-1 can be a promising candidate for anticancer therapy.

Placebo-Controlled Randomized Trial of an Intestinal Bile Salt Transport Inhibitor for Pruritus in Alagille Syndrome

Medically refractory, severe, cholestasis-induced pruritus in Alagille syndrome may be improved by surgical interruption of the enterohepatic circulation. This multicenter trial (NCT02057692) tested the hypothesis that the intestinal bile acid transport inhibitor maralixibat would similarly reduce pruritus in Alagille syndrome. Thirty-seven children with Alagille syndrome were randomly assigned to double-blinded administration of placebo, 70, 140, or 280 µg/kg/day of maralixibat for 13 weeks. Pruritus was assessed by caregiver (itch-reported outcome instrument [ItchRO]) and clinician report (range, 0-4 [severe]). Liver chemistries and serum bile acids were measured. The primary outcome was the change from baseline to week 13 in ItchRO relative to placebo. In the a priori first analysis of the primary efficacy endpoint, the mean adjusted difference between participants receiving 140 or 280 µg/kg/day and placebo was -0.47 (95% confidence interval [CI], -1.14, 0.20; P = 0.16). Statistically significant decreases were observed with doses of 70 and 140 µg/kg/day (mean adjusted difference, -0.89; 95% CI, -1.70, -0.08; P = 0.032; and mean adjusted difference, -0.91; 95% CI, -1.62, -0.19; P = 0.014) but not 280 µg/kg/day (mean adjusted difference, -0.04; 95% CI, -0.94, 0.86; P = 0.44) or all doses combined (mean adjusted difference, -0.61; 95% CI, -1.24, 0.20; P = 0.055). A 1-point reduction in pruritus was more common in maralixibat-treated versus placebo-treated participants (caregiver ItchRO, 65% versus 25%; P = 0.06; clinician score, 76% versus 25%; P = 0.01). There were no significant changes in liver chemistries or bile acids relative to placebo. Adverse and serious adverse events were similar between maralixibat and placebo. Conclusion: Although the prespecified primary analyses of ItchRO were not all statistically significant, the data suggest that maralixibat is safe and may reduce pruritus in Alagille syndrome.

Complement drives neurodegeneration in Gaucher disease

GBA1 mutations result in excess storage of glucosylceramide (GC) and the induction of Gaucher disease (GD). GD is frequently associated with elevated levels of pro-inflammatory cytokines and the development of brain inflammation. The mechanisms underlying GC-driven brain inflammation in GD are ill-defined. Recently, we described immune complexes of GC-specific IgG autoantibodies in experimental and clinical GD, which induced massive complement activation and C5a generation. Further, we found that C5a-mediated activation of its cognate C5a receptor 1 (C5aR1) tips the balance between GC formation and degradation, thereby fueling excess GC accumulation and inflammation in visceral tissues in experimental and clinical GD.

Previously, the C5a/C5aR1 axis was found to regulate the blood brain barrier integrity in systemic lupus and promote neurodegeneration in Alzheimer’s disease. Here, we determined the production of C5a in the brain of Gba1 D409V/knockout (9V/null) GD-prone mice. C5a production in the brain of 9V/null mice was markedly elevated, when compared to WT control mice. Also, 9V/null mice suffered from massive accumulation of GC in the brain and loss of neurons. To assess the relevance of C5a/C5aR1 axis activation for brain inflammation in GD, we targeted glucocerebrosidase (GCase) with conduritol B epoxide (CBE) in WT and C5aR1−/− mice. Strikingly, CBE-injected WT mice died within 30 days. In contrast, all C5aR1−/− mice survived the 60 days observation window, were protected from CBE-induced accumulation of GC in the brain, showed a marked reduction of microglial cell activation and only a minor loss of neurons. Our data suggest that the C5a/C5aR1 axis is a critical driver of neurodegeneration in experimental GD.

Complement drives glucosylceramide accumulation and tissue inflammation in Gaucher disease

Gaucher disease is caused by mutations in GBA1, which encodes the lysosomal enzyme glucocerebrosidase (GCase). GBA1 mutations drive extensive accumulation of glucosylceramide (GC) in multiple innate and adaptive immune cells in the spleen, liver, lung and bone marrow, often leading to chronic inflammation. The mechanisms that connect excess GC to tissue inflammation remain unknown. Here we show that activation of complement C5a and C5a receptor 1 (C5aR1) controls GC accumulation and the inflammatory response in experimental and clinical Gaucher disease. Marked local and systemic complement activation occurred in GCase-deficient mice or after pharmacological inhibition of GCase and was associated with GC storage, tissue inflammation and proinflammatory cytokine production. Whereas all GCase-inhibited mice died within 4-5 weeks, mice deficient in both GCase and C5aR1, and wild-type mice in which GCase and C5aR were pharmacologically inhibited, were protected from these adverse effects and consequently survived. In mice and humans, GCase deficiency was associated with strong formation of complement-activating GC-specific IgG autoantibodies, leading to complement activation and C5a generation. Subsequent C5aR1 activation controlled UDP-glucose ceramide glucosyltransferase production, thereby tipping the balance between GC formation and degradation. Thus, extensive GC storage induces complement-activating IgG autoantibodies that drive a pathway of C5a generation and C5aR1 activation that fuels a cycle of cellular GC accumulation, innate and adaptive immune cell recruitment and activation in Gaucher disease. As enzyme replacement and substrate reduction therapies are expensive and still associated with inflammation, increased risk of cancer and Parkinson disease, targeting C5aR1 may serve as a treatment option for patients with Gaucher disease and, possibly, other lysosomal storage diseases.

Chemical synthesis of [(13)c]daidzein

Pharmacokinetic and metabolic studies of phytoestrogens of the isoflavone class have been hampered by the lack of suitable stable-isotope-labeled analogs. A method for preparation of a [(13)C]-labeled analog of daidzein is described. [2-(13)C]Daidzein was synthesized by reaction of [(13)C]diethoxydimethylaminomethane with 2,4-dihydroxybenzoin. The final product was purified to more than 99% by reverse-phase high-performance liquid chromatography and structural analysis confirmed by nuclear magnetic resonance spectroscopy and mass spectrometry. Because [2-(13)C]daidzein is analytically and metabolically stable, it is a suitable analog for use as an internal standard for quantifying daidzein in biological fluids using isotope dilution mass spectrometry. This nonradioactive tracer is also ideal for investigating the pharmacokinetics of daidzein in humans because it is biologically indistinguishable from the unlabeled form.

Weight loss induced by Roux-en-Y gastric bypass but not laparoscopic adjustable gastric banding increases circulating bile acids

CONTEXT

It has been hypothesized that increased plasma bile acids (BAs) contribute to metabolic improvements after Roux-en-Y gastric bypass (RYGB) surgery by the G protein-coupled receptor TGR5-mediated effects on glucagon-like peptide-1 secretion and thyroid hormones.

OBJECTIVE

The objective of this study was to evaluate the importance of bariatric surgery-induced alterations in BA physiology on factors that regulate glucose homeostasis (insulin secretion and sensitivity) and energy metabolism (resting energy expenditure and thyroid hormone axis). DESIGN, PARTICIPANTS, INTERVENTION, AND MAIN OUTCOME MEASURE: Eighteen extremely obese subjects were studied before and after 20% weight loss, induced by either laparoscopic adjustable gastric banding (LAGB) (n = 10) or RYGB surgery (n = 8).

RESULTS

Plasma BAs more than doubled after RYGB [fasting: 1.08 (0.26-1.42) to 2.28 (1.59-3.28) μmol/L, P = .03; postprandial: 2.46 ± 1.59 to 6.00 ± 2.75 μmol/L, P = .01] but were either lower or did not change after LAGB [fasting: 1.80 (1.49-2.19) to 0.92 (0.73-1.15) μmol/L, P = .02; postprandial: 3.71 ± 2.61 to 2.82 ± 1.75 μmol/L, P = .14]. Skeletal muscle expression of TGR5 targets, Kir6.2 and cyclooxygenase IV, increased after RYGB but not LAGB. Surgery-induced changes in BAs were associated with increased peak postprandial plasma glucagon-like peptide-1 (r(2) = 0.509, P = .001) and decreased serum TSH (r(2) = 0.562, P < .001) but did not correlate with the change in insulin response to a meal (r(2) = 0.013, P = .658), insulin sensitivity (assessed as insulin stimulated glucose disposal during a hyperinsulinemic-euglycemic clamp procedure) (r(2) = 0.001, P = .995), or resting energy expenditure (r(2) = 0.004, P = .807).

CONCLUSIONS

Compared with LAGB, RYGB increases circulating BAs and TGR5 signaling, but this increase in BAs is not a significant predictor of changes in glucose homeostasis or energy metabolism.

Adaptive regulation of bile salt transporters in kidney and liver in obstructive cholestasis in the rat

BACKGROUND & AIMS

Cholestasis results in adaptive regulation of bile salt transport proteins in hepatocytes that may limit liver injury. However, it is not known if changes also occur in the expression of bile salt transporters that reside in extrahepatic tissues, particularly the kidney, which might facilitate bile salt excretion during obstructive cholestasis.

METHODS

RNA and protein were isolated from liver and kidney 14 days after common bile duct ligation in rats and assessed by RNA protection assays, Western analysis, and tissue immunofluorescence. Sodium-dependent bile salt transport was also measured in brush border membrane vesicles from the kidney.

RESULTS

After common bile duct ligation, serum bile salts initially rose and then declined to lower levels after 3 days. In contrast, urinary bile salt excretion rose progressively over the 2-week period. By that time, the ileal sodium-dependent bile salt transporter messenger RNA and protein expression in total liver had increased to 300% and 200% of controls, respectively, while falling to 46% and 37% of controls, respectively, in the kidney. Sodium-dependent uptake of (3)H-taurocholate in renal brush border membrane vesicles was decreased. In contrast, the multidrug resistance-associated protein 2 expression in the kidney was increased 2-fold, even 1 day after ligation. Immunofluorescent studies confirmed the changes in the expression of these transporters in liver and kidney.

CONCLUSIONS

These studies show that the molecular expression of bile salt transporters in the kidney and cholangiocytes undergo adaptive regulation after common bile duct obstruction in the rat. These responses may facilitate extrahepatic pathways for bile salt excretion during cholestasis.

Soy isoflavones--benefits and risks from nature's selective estrogen receptor modulators (SERMs)

Phytoestrogens have become one of the more topical areas of interest in clinical nutrition. These non-nutrient bioactive compounds are ubiquitous to the plant kingdom and possess a wide range of biological properties that contribute to the many different health-related benefits reported for soy foods and flaxseeds--two of the most abundant dietary sources of phytoestrogens. Reviewed is the recent knowledge related to their pharmacokinetics and clinical effects, focusing mainly on isoflavones that are found in high concentrations in soy foods. Arguments are made for considering soy isoflavones as natural selective estrogen receptor modulators (SERMs) based upon recent data of their conformational binding to estrogen receptors. Rebuttal is made to several key and important issues related to the recent concerns about the safety of soy and its constituent isoflavones. This article is not intended to be a comprehensive review of the literature but merely highlight recent research with key historical perspectives.

Altered sexually dimorphic nucleus of the preoptic area (SDN-POA) volume in adult Long-Evans rats by dietary soy phytoestrogens

Naturally occurring estrogen-like molecules in plants (phytoestrogens), present via soy, in animal diets can alter morphology and physiology in rodents. Phytoestrogens have the ability to bind estrogen receptors and exert many of the biological responses evoked by physiological estrogens. This study characterized the effects of dietary phytoestrogens on the expression of body and prostate weight, circulating testosterone and estradiol levels, puberty onset, vaginal cyclicity, and volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) in Long-Evans rats. Using different experimental protocols, animals were fed either a phytoestrogen-rich (Phyto-600) or a phytoestrogen-free (Phyto-free) diet. Animals fed the Phyto-600 diet displayed significantly decreased body weights (in males and females), prostate weights and delayed puberty in females compared to that of animals fed the Phyto-free diet. Circulating testosterone or estradiol levels in males or estrous cyclicity were not altered by the diets. The volume of the SDN-POA was significantly altered by a change in diet at 80 days of age where one-half of the males or females fed the Phyto-600 diet (from birth) were switched to the Phyto-free diet until 120 days of age. Males initially fed a Phyto-600 diet but changed to a Phyto-free diet had significantly smaller SDN-POA volumes compared to males fed the Phyto-600 diet (long-term). These data suggest that consumption of phytoestrogens via a soy diet, significantly: (1) decreases body and prostate weight, (2) delays puberty onset, and (3) alters SDN-POA volumes during adulthood.

Dietary inclusion of whole soy foods results in significant reductions in clinical risk factors for osteoporosis and cardiovascular disease in normal postmenopausal women

OBJECTIVE

To determine the effects of dietary inclusion of soy foods on clinical markers for cardiovascular disease (CVD) and osteoporosis in normal postmenopausal women.

DESIGN

This was a single open-group prospective clinical intervention. Forty-two normal postmenopausal women consumed three daily servings for 12 consecutive weeks of whole soy foods containing approximately 60 mg/d of isoflavones. Blood and urine specimens were obtained at baseline and after 12 weeks of dietary intervention.

RESULTS

Serum and urine levels of individual and total isoflavones increased significantly (7-19 fold, p < 0.001) from baseline. A significant increase (9.3%, p < 0.05) in the mean lag-time of low-density lipoprotein cholesterol oxidation was seen and was positively correlated with serum phytoestrogens (p < 0.05). Significant increases were found in mean levels of high-density lipoprotein cholesterol (HDLc) (3.7%, p < 0.05) and serum osteocalcin (10.2%, p < 0.025). Significant decreases were observed in total cholesterol:HDLc ratios (5.5%, p < 0.006) and mean urinary N-telopeptide excretion (13.9%, p < 0.02). Urinary excretion of total isoflavones was negatively correlated with very-low-density lipoprotein cholesterol, triglycerides, and total cholesterol:HDLc ratios (p < 0.04). No significant changes from baseline in HDLc peroxidation, total cholesterol, triglycerides, low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, bone-specific alkaline phosphatase, follicle-stimulating hormone, or estradiol levels were observed.

CONCLUSIONS

Dietary inclusion of whole soy foods containing 60 mg/d of isoflavones results in significant serum levels of phytoestrogens and reductions in several key clinical risk factors for CVD and osteoporosis in normal postmenopausal women. Long-term, placebo-controlled clinical trials are needed to evaluate the effect of phytoestrogens on the clinical endpoints of CVD and osteoporosis in this population.

Dietary soy-phytoestrogens decrease testosterone levels and prostate weight without altering LH, prostate 5alpha-reductase or testicular steroidogenic acute regulatory peptide levels in adult male Sprague-Dawley rats

Nutritional factors, especially phytoestrogens, have been extensively studied for their potential beneficial effects against hormone-dependent and age-related diseases. The present study describes the short-term effects of dietary phytoestrogens on regulatory behaviors (food/water intake, locomotor activity and body weight), prostate weight, prostate 5alpha-reductase enzyme activity, reproductive hormone levels, and testicular steroidogenic acute regulatory peptide (StAR) levels in adult Sprague-Dawley rats. Animals were fed either a phytoestrogen-rich diet containing approximately 600 microg/g isoflavones (as determined by HPLC) or a phytoestrogen-free diet. After 5 weeks of consuming these diets, plasma phytoestrogen levels were 35 times higher in animals fed the phytoestrogen-rich vs phytoestrogen-free diets. Body and prostate weights were significantly decreased in animals fed the phytoestrogen-rich diet vs the phytoestrogen-free fed animals; however, no significant change in prostate 5alpha-reductase enzyme activity was observed between the treatment groups. Locomotor activity levels were higher in the phytoestrogen-rich vs the phytoestrogen-free animals during the course of the treatment interval. Plasma testosterone and androstenedione levels were significantly lower in the animals fed the phytoestrogen-rich diet compared with animals fed the phytoestrogen-free diet. However, there were no significant differences in plasma LH or estradiol levels between the diet groups. Testicular StAR levels were not significantly different between the phytoestrogen-rich vs the phytoestrogen-free fed animals. These results indicated that consumption of dietary phytoestrogens resulting in very high plasma isoflavone levels over a relatively short period can significantly alter body and prostate weight and plasma androgen hormone levels without affecting gonadotropin or testicular StAR levels. The findings of this study identify the biological actions of phytoestrogens on male reproductive endocrinology and provide insights into the protective effects these estrogen mimics exert in male reproductive disorders such as benign prostatic hyperplasia and prostate cancer.

Myocardial Akt Activation and Gender

Abstract —Cardiovascular disease risk is higher in men than women, but the basis for this discrepancy remains controversial. Estrogenic stimulation of the myocardium or isolated cardiomyocytes has been purported to exert multiple beneficial effects associated with inhibition of maladaptive responses to pathogenic insults. This report describes a significant difference between the sexes in myocardial activation of Akt, a protein kinase that regulates a broad range of physiological responses including metabolism, gene transcription, and cell survival. We find that young women possess higher levels of nuclear-localized phospho-Akt 473 relative to comparably aged men or postmenopausal women. Both localization of phospho-Akt 473 in myocardial nuclei of sexually mature female mice versus males and Akt kinase activity in nuclear extracts of hearts from female mice versus males are elevated. Cytosolic localization of phospho-forkhead, a downstream nuclear target of Akt, is also increased in female relative to male mice, suggesting a potential mechanism for cardioprotective nuclear signaling resulting from Akt activation. Phospho-Akt 473 levels and localization at cardiac nuclei are similarly increased in transgenic mice with myocardium-specific expression of insulin-like growth factor I, a proven stimulus for Akt activation. Phospho-Akt 473 is also localized to the nucleus of cultured cardiomyocytes after exposure to 17β-estradiol or genistein (a phytoestrogen in soy protein–based diets), and neonatal exposure of litters to genistein elevated nuclear phospho-Akt 473 localization. The activation of Akt in a gender-dependent manner may help explain differences observed in cardiovascular disease risk between the sexes and supports the potential beneficial effects of estrogenic stimulation.

Animal models impacted by phytoestrogens in commercial chow: implications for pathways influenced by hormones

It is generally not known that most commercial rodent diets are formulated with soy protein and deliver large daily doses of isoflavones to animals throughout their lifespan, including the in utero period. Here, we demonstrate that isoflavones are bioavailable and show that commercial rodent diets universally used by animal facilities lead to very high steady-state serum isoflavone concentrations in adult rats (2613 +/- 873 ng/mL) and mice (2338 +/- 531 ng/mL), exceeding the animal's endogenous estrogen level by 30,000- to 60,000-fold. We demonstrate the maternal-fetal intrauterine transfer of isoflavones in animals fed a standard Purina 5001 soy-containing diet and show that newborn rat pups have high serum isoflavones levels (540 +/- 174 ng/mL) that are maintained throughout the suckling period by passage of isoflavones into maternal milk. These findings have profound implications for all animal experiments, including multigenerational studies and studies of transgenic animals, especially if biochemical or morphological end-points are influenced by the hormonal or nonhormonal properties of phytoestrogens. These compounds have the potential to modulate genotypic and phenotypic expression in general, and therefore, all investigators should be vigilant to the phytoestrogen composition of commercial rodent diets because there is a history of potent biological effects in larger animals and in humans from high circulating isoflavone concentrations.

Analytical performance of luminescent immunoassays of different format for serum daidzein analysis

Two sensitive competitive-type solid-phase immunoassays for serum daidzein analysis have been developed and optimized. The first is a chemiluminescent enzyme immunoassay that uses black polystyrene microtiter wells in which daidzein-specific antibodies raised in rabbits are immobilized and a daidzein derivative is coupled to horseradish peroxidase (HRP) as a label. The HRP activity of the antibody-bound tracer is measured with an enhanced chemiluminescent system (luminol/H2O2/enhancer). The second immunoassay is based on the use of bovine serum albumin-daidzein derivative immobilized on microtiter plates and a secondary anti-rabbit IgG-Fc fragment conjugated with 4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-dicarboxylic acid (BCPDA). Formation of the complex Eu3+-BCPDA enables time-resolved fluorescence-mode detection of the amount of antibody bound to the immobilized antigen. Both methods fulfilled all the requirements of accuracy and precision. The detection limit was the same for each method, 10 pg/well; this is better than that of other immunoassays. The specificity of the two methods was different, because of their competitive-type mechanisms. The performance of the chemiluminescence method is better, because the cross-reactivity of the main interfering compound (genistein) was 5%, compared with 25% for the time-resolved fluoroimmunoassay.

Modulation of steady-state messenger RNA levels in the regenerating rat liver with bile acid feeding

Liver regeneration after two thirds partial hepatectomy (PH) is an orchestrated hyperplastic growth process requiring coordinated expression of many genes. The synchronous progression of 95% of the remnant hepatocytes through the cell cycle provides an in vivo model for examining the influence of bile acids on the molecular regulation of hepatocyte replication and growth. In this study, we examined the effects of endogenous deoxycholic acid (DCA) and ursodeoxycholic acid (UDCA) on messenger RNA (mRNA) expression and growth rate during liver regeneration. Rats were fed diets containing no addition, 0.4% DCA, UDCA, or both for 14 days; they then underwent 70% PH and were maintained on the diets for an additional 14 days. mRNA transcript levels for a variety of cell cycle-regulated genes were examined post-PH by Northern blot analysis. Bile acid concentrations were determined in liver, isolated nuclei, and plasma by gas chromatography and mass spectrometry. The results indicated that the addition of DCA and UDCA to the diet markedly shifted the bile-acid compositions of liver and plasma. In addition, DCA dramatically altered the abundance of many transcripts post-PH, whereas coadministration of UDCA suppressed the effect. DCA feeding significantly inhibited liver growth through day 3; however, by day 8, it induced an approximately 20% increase in mass compared with controls, UDCA-fed, or combination-fed animals. UDCA was concentrated greater than 20-fold in nuclei compared with whole liver in controls and DCA-fed animals and greater than 2-fold with UDCA feeding. These data suggest that bile acids may have a key role in liver regeneration, which is significantly altered by modulation of the bile-acid pool.

Bioavailability of pure isoflavones in healthy humans and analysis of commercial soy isoflavone supplements

The pharmacokinetic behavior of naturally occurring isoflavones has been determined for the first time in healthy adults. We compared plasma kinetics of pure daidzein, genistein and their beta-glycosides administered as a single-bolus dose to 19 healthy women. This study demonstrates differences in the pharmacokinetics of isoflavone glycosides compared with their respective beta-glycosides. Although all isoflavones are efficiently absorbed from the intestinal tract, there are striking differences in the fate of aglycones and beta-glycosides. Mean time to attain peak plasma concentrations (t(max)) for the aglycones genistein and daidzein was 5.2 and 6.6 h, respectively, whereas for the corresponding beta-glycosides, the t(max) was delayed to 9.3 and 9.0 h, respectively, consistent with the residence time needed for hydrolytic cleavage of the glycoside moiety for bioavailability. The apparent volume of distribution of isoflavones confirms extensive tissue distribution after absorption. Plasma genistein concentrations are consistently higher than daidzein when equal amounts of the two isoflavones are administered, and this is accounted for by the more extensive distribution of daidzein (236 L) compared with genistein (161 L). The systemic bioavailability of genistein [mean AUC = 4.54 microg/(mL x h)] is much greater than that of daidzein [mean AUC = 2.94 microg/(mL x h)], and bioavailability of these isoflavones is greater when ingested as beta-glycosides rather than aglycones as measured from the area under the curve of the plasma appearance and disappearance concentrations. The pharmacokinetics of methoxylated isoflavones show distinct differences depending on the position of the methoxyl group in the molecule. Glycitin, found in two phytoestrogen supplements, underwent hydrolysis of the beta-glycoside moiety and little further biotransformation, leading to high plasma glycitein concentrations. Biochanin A and formononetin, two isoflavones found in one phytoestrogen supplement, were rapidly and efficiently demethylated, resulting in high plasma genistein and daidzein concentrations typically observed after the ingestion of soy-containing foods. These differences in pharmacokinetics and metabolism have implications for clinical studies because it cannot be assumed that all isoflavones are comparable in their pharmacokinetics and bioavailability. An analysis of 33 phytoestrogen supplements and extracts revealed considerable differences in the isoflavone content from that claimed by the manufacturers. Plasma concentrations of isoflavones show marked qualitative and quantitative differences depending on the type of supplement ingested. These studies indicate a need for improvement in quality assurance and standardization of such products.

Maternal and perinatal brain aromatase: effects of dietary soy phytoestrogens

Phytoestrogens are extensively investigated for their potential to prevent many hormone-dependent cancers and age-related diseases, however little is known about their effects in brain. Brain aromatase and plasma phytoestrogen levels were determined in Sprague-Dawley rats fed a phytoestrogen-rich diet during pregnancy/lactation. Ingested phytoestrogens cross the placenta and become concentrated in maternal milk as evident from high infantile plasma concentrations. Dietary phytoestrogens, however, do not alter brain aromatase during pregnancy/lactation or perinatal development.

A randomized double blind-cross over trial of soya protein for the treatment of cyclical breast pain

Twenty patients with cyclical breast pain were enrolled in a double-blind cross-over trial in which either a soy protein drink or a flavoured cow's milk was taken orally each day for 3 months before crossing over to the alternate drink for a further 3 months. Records of pain scores were taken throughout the study. Blood was also taken before and after 3 and 6 months for the measurement of phytoestrogents to assess compliance. Two women withdrew from the study at the outset leaving 18 evaluable patients who completed the study. Of these 10 (56%) felt that soy protein improved breast pain (two of whom received soy as first treatment) and two (11%) felt that cow's milk alleviated symptoms (one receiving this as first preparation) and the remaining six (33%) experienced no relief of pain with either dietary preparation. Blood levels of diadzein and genistein were elevated after the ingestion of soy protein in only 13 patients (seven of whom felt that soy improved their breast pain); in the remaining five patients (three of whom suggested that soy protein improved breast pain) phytoestrogen levels were no higher than pretreatment values. Although the ingestion of soy protein may be associated with relief of breast pain, these results illustrate the problem of non-specific effects in studies of mastalgia in that 1) cow's milk also relieved breast pain in some patients and 2) that the benefits of soy protein were not always associated with evidence of elevated circulating levels of phyto-estrogens, indicating the difficulty of compliance in dietary intervention studies using soy foods.

Phytoestrogens decrease brain calcium-binding proteins but do not alter hypothalamic androgen metabolizing enzymes in adult male rats

Phytoestrogen [plant estrogenic-like molecule(s)] research has grown rapidly in recent years due to their potential health benefits. However, little is known about phytoestrogen's effects on the CNS. Androgen metabolizing enzymes are known to regulate neuroendocrine functions and reproductive behaviors, while calcium-binding proteins are associated with protecting against neurodegenerative diseases. Therefore, we examined aromatase and 5alpha-reductase enzyme activities in the medial basal hypothalamic and preoptic area (mbh-poa) and characterized mbh-poa and amygdala (amy) calbindin and calretinin levels (via Western analysis) from animals fed a phytoestrogen-free (P-free) vs. a phytoestrogen-containing diet [(P-600); that had 600 microg/g of phytoestrogens]. After approximately 5 weeks on the diets, the male rats were killed at 105 days. P-600 plasma phytoestrogen levels were 78-fold higher than the P-free values and the mbh-poa phytoestrogen content was 8-fold higher than the P-free group, demonstrating the passage of phytoestrogens into brain. In general, brain aromatase or 5alpha-reductase activity levels were not significantly altered by the experimental diets. However, independent of brain site (i.e., mbh-poa or amy) the abundance of calbindin from male P-600 rats was significantly lower than P-free animals. Conversely, for calretinin there were no significant alterations in the mbh-poa tissue site, while in the amy a similar pattern of expression was seen to that of the calbindin results. These data suggest that consumption of phytoestrogens via a soy diet for a relatively short interval can significantly: (1) elevate plasma and brain phytoestrogens levels and (2) decrease brain calcium-binding proteins without altering brain androgen metabolizing enzymes.

Serum unconjugated bile acids as a test for intestinal bacterial overgrowth in dogs

Small intestinal bacterial overgrowth (SIBO) has a high incidence in dogs and, as in humans, is difficult to diagnose. The aim of this study was to determine the diagnostic significance of serum unconjugated bile acid concentrations in dogs with bacterial overgrowth. Fasting sera were obtained from 23 dogs: 10 with culture-proven SIBO, 8 with indirectly diagnosed SIBO (normal pancreatic function but small intestinal disease associated with subnormal serum cobalamin and supranormal folate concentrations), and 5 healthy controls. Unconjugated bile acids were determined using gas chromatography-mass spectrometry after isolation by liquid-solid extraction and anion-exchange chromatography. Mean serum unconjugated bile acid concentrations were significantly elevated in dogs with SIBO (mean +/- SD: 0.91 +/- 1.03 micromol/liter), and in dogs with indirectly diagnosed SIBO (2.11 +/- 2.20 micromol/liter) compared to clinically healthy dogs (0.015 +/- 0.015 micromol/liter, P < 0.005). Cholic acid was the predominant unconjugated bile acid in the serum of dogs with SIBO. In conclusion serum unconjugated bile acid concentrations of healthy dogs are significantly lower than reported values for humans, and this fraction represents a relatively small proportion (0-2.3%; mean 0.8%) of the total bile acids in dogs. Unconjugated bile acids increased 10- to 20-fold in dogs with SIBO indicating the clinical utility of serum unconjugated bile acids for diagnosis of intestinal bacterial overgrowth in dogs.

Inhibition of CYP1A1 enzyme activity in mouse hepatoma cell culture by soybean isoflavones

The mechanisms by which soybean- and soybean isoflavone-enriched diets inhibit carcinogenesis are not known. We found that the isoflavones genistin and daidzin, and their respective aglucone forms daidzein and genistein, block 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; dioxin)-induced CYP1A1 enzyme activity. This inhibition is correlated with the capacity of the isoflavones to prevent CYP1A1-mediated covalent binding of benzo[a]pyrene (BaP) metabolites to DNA. We further evaluated daidzein and genistein, believed to be the active forms of the isoflavones, for the mechanism of the inhibitory process. Although daidzein and genistein appear structurally similar to known aromatic hydrocarbon receptor (AHR) agonists and antagonists, gel mobility shift assays indicated that the isoflavones do not inhibit dioxin-induced activation of the AHR or the accumulation of CYP1A1 mRNA, suggesting that the isoflavones do not act at the transcriptional level. We therefore evaluated the isoflavones for direct effects on the CYP1A1 enzyme. Daidzein and genistein non-competitive with the CYP1A1 substrate BaP for microsomal BaP hydroxylation, with apparent Ki values of 325 microM and 140 microM, respectively. The extent of CYP1A1 inhibition increases with time of preincubation at 37 degrees C, but not at 4 degrees C, in the presence of isoflavone plus NADPH; after 60 min preincubation the inhibition remains non-competitive, with apparent Ki values of 55 microM and 50 microM, respectively. Inhibition is neither prevented nor reversed by the thiol antioxidant dithiothreitol, nor by the iron chelator deferoxamine. Repeated washing of the microsomes does not reverse the inhibition. The dependency on NADPH, temperature and time for inhibition of CYP1A1 suggests that metabolism of either isoflavone or molecular oxygen to reactive species is required. Isoflavone-mediated inhibition of CYP1A1 activity may contribute to the mechanism by which these soybean isoflavones protect against carcinogenesis.

Phytoestrogen content of purified, open- and closed-formula laboratory animal diets

BACKGROUND AND PURPOSE

Phytoestrogens exert estrogenic effects on the central nervous system, induce estrus, and stimulate growth of the genital tract of female animals. Over 300 plants and plant products, including some used in laboratory animal diets, contain phytoestrogens. Therefore, the source and concentration of phytoestrogens in rodent diets were determined.

METHODS

Twelve rodent diets and six major dietary ingredients were assayed for phytoestrogens (daidzein, genistein, formononetin, biochanin A, and coumestrol), using high-performance liquid chromatography. Three rodent diets recently formulated to reduce phytoestrogen content also were assayed.

RESULTS

Formononetin, biochanin A, and coumestrol were not detected. Soybean meal was the major source of daidzein and genistein; their concentrations were directly correlated to the percentage of soybean meal in each diet.

CONCLUSIONS

High, variable concentrations of daidzein and genistein are present in some rodent diets, and dietary phytoestrogens have the potential to alter results of studies of estrogenicity. Careful attention should be given to diet phytoestrogen content, and their concentration should be reported. A standardized, open-formula diet in which estrogenic substances have been reduced to levels that do not alter results of studies that are influenced by exogenous estrogens is recommended.

Brain aromatase and 5alpha-reductase, regulatory behaviors and testosterone levels in adult rats on phytoestrogen diets

The purpose of this study was to examine the short-term effects of phytoestrogens in the diet on regulatory behaviors (food/water intake and locomotor activity), prostate weight, testosterone levels, and brain androgen metabolizing enzyme activity levels in adult male rats. Sprague-Dawley rats were fed phytoestrogen-containing versus phytoestrogen-free diets for 29 days. Standard methods were used to measure open field behavior, reproductive, hormonal parameters, and enzymatic activity levels. The phytoestrogen diet contained approximately 200 microg/g of isoflavones whereas in the phytoestrogen-free diet, no phytoestrogens were detected by HPLC analysis. There were no significant differences in any of the regulatory behaviors (food/water intake or locomotor activity), prostate weight, or testosterone levels between the treatment groups. Furthermore, there was no significant influence of phytoestrogens on brain aromatase activity levels, in either the medial basal hypothalamic-preoptic area (MBH-POA) or amygdala brain tissue sites examined. However, significant alterations in MBH-POA and amygdala 5alpha-reductase activities were detected in animals receiving the phytoestrogen-containing versus the phytoestrogen-free diets.

Dietary isoflavones: biological effects and relevance to human health

Substantial evidence indicates that diets high in plant-based foods may explain the epidemiologic variance of many hormone-dependent diseases that are a major cause of mortality and morbidity in Western populations. There is now an increased awareness that plants contain many phytoprotectants. Lignans and isoflavones represent two of the main classes of phytoestrogens of current interest in clinical nutrition. Although ubiquitous in their occurrence in the plant kingdom, these bioactive nonnutrients are found in particularly high concentrations in flaxseeds and soybeans and have been found to have a wide range of hormonal and nonhormonal activities that serve to provide plausible mechanisms for the potential health benefits of diets rich in phytoestrogens. Data from animal and in vitro studies provide convincing evidence for the potential of phytoestrogens in influencing hormone-dependent states; although the clinical application of diets rich in these estrogen mimics is in its infancy, data from preliminary studies suggest beneficial effects of importance to health. This review focuses on the more recent studies pertinent to this field and includes, where appropriate, the landmark and historical literature that has led to the exponential increase in interest in phytoestrogens from a clinical nutrition perspective.

Differences in the metabolism and disposition of ursodeoxycholic acid and of its taurine-conjugated species in patients with primary biliary cirrhosis

The clinical effectiveness of ursodeoxycholate in the treatment of liver disease may be limited by its poor absorption and extensive biotransformation. Because in vitro and in vivo studies suggest that the more hydrophilic bile acid tauroursodeoxycholate has greater beneficial effects than ursodeoxycholate, we have compared for the first time the absorption, metabolism, and clinical responses to these bile acids in patients with primary biliary cirrhosis (PBC). Twelve female patients with PBC were sequentially administered tauroursodeoxycholate and ursodeoxycholate (750 mg/d for 2 months) in a randomized, cross-over study. Bile acids were measured in serum, duodenal bile, urine, and feces by gas chromatography-mass spectrometry (GC-MS). Biliary ursodeoxycholate enrichment was higher during tauroursodeoxycholate administration (32.6% vs. 29.2% during ursodeoxycholate; P <.05). Lithocholic acid concentration was consistently higher in all biological fluids during ursodeoxycholate administration. Fecal bile acid excretion was the major route of elimination of both bile acids; ursodeoxycholate accounted for 8% and 23% of the total fecal bile acids during tauroursodeoxycholate and ursodeoxycholate administration, respectively (P <.05). Tauroursodeoxycholate was better absorbed than ursodeoxycholate, and, although it was partially deconjugated and reconjugated with glycine, it underwent reduced biotransformation to more hydrophobic metabolites. This comparative study suggests that tauroursodeoxycholate has significant advantages over ursodeoxycholate that may be of benefit for long-term therapy in PBC.

Isoflavone content of infant formulas and the metabolic fate of these phytoestrogens in early life

Soy-based infant formulas have been in use for >30 y. These formulas are manufactured from soy protein isolates and contain significant amounts of phytoestrogens of the isoflavone class. As determined by HPLC, the isoflavone compositions of commercially available formulas are similar qualitatively and quantitatively and are consistent with the isoflavone composition of soy protein isolates. Genistein, found predominantly in the form of glycosidic conjugates, accounts for >65% of the isoflavones in soy-based formulas. Total isoflavone concentrations of soy-based formulas prepared for infant feeding range from 32 to 47 mg/L, whereas isoflavone concentrations in human breast milk are only 5.6 +/- 4.4 microg/L (mean +/- SD, n = 9). Infants fed soy-based formulas are therefore exposed to 22-45 mg isoflavones/d (6-11 mg x kg body wt(-1) x d(-1)), whereas the intake of these phytoestrogens from human milk is negligible (<0.01 mg/d). The metabolic fate of isoflavones from soy-based infant formula is described. Plasma isoflavone concentrations reported previously for 4-mo-old infants fed soy-based formula were 654-1775 microg/L (mean: 979.7 microg/L: Lancet 1997:350;23-7), significantly higher than plasma concentrations of infants fed either cow-milk formula (mean +/- SD: 9.4 +/- 1.2 microg/L) or human breast milk (4.7 +/- 1.3 microg/L). The high steady state plasma concentration of isoflavones in infants fed soy-based formula is explained by reduced intestinal biotransformation, as evidenced by low or undetectable concentrations of equol and other metabolites, and is maintained by constant daily exposure from frequent feeding. Isoflavones circulate at concentrations that are 13,000-22,000-fold higher than plasma estradiol concentrations in early life. Exposure to these phytoestrogens early in life may have long-term health benefits for hormone-dependent diseases.

Phytoestrogens: the biochemistry, physiology, and implications for human health of soy isoflavones

The importance of estrogens in homeostatic regulation of many cellular and biochemical events is well illustrated by the pathophysiologic changes that occur with estrogen deficiency. Many of the major diseases of Western populations are hormone dependent and epidemiologic data have shown a strong association between their incidence and diet. In particular, the importance of a plant-based diet is evident from the current dietary recommendations that emphasize an increase in the proportion and amount of fruit and vegetables that should be consumed. Although interpretation of the role of individual components of the diet is difficult from epidemiologic and dietary studies, it is recognized that there are many plant-derived bioactive nonnutrients that can confer significant health benefits. Among these phytochemicals is the broad class of nonsteroidal estrogens called phytoestrogens, and in the past decade there has been considerable interest in the role of isoflavones because of their relatively high concentrations in soy protein. The isoflavones in modest amounts of ingested soy protein are biotransformed by intestinal microflora, are absorbed, undergo enterohepatic recycling, and reach circulating concentrations that exceed by several orders of magnitude the amounts of endogenous estrogens. These phytoestrogens and their metabolites have many potent hormonal and nonhormonal activities that may explain some of the biological effects of diets rich in phytoestrogens.

Identification of a new inborn error in bile acid synthesis: mutation of the oxysterol 7alpha-hydroxylase gene causes severe neonatal liver disease

We describe a metabolic defect in bile acid synthesis involving a deficiency in 7alpha-hydroxylation due to a mutation in the gene for the microsomal oxysterol 7alpha-hydroxylase enzyme, active in the acidic pathway for bile acid synthesis. The defect, identified in a 10-wk-old boy presenting with severe cholestasis, cirrhosis, and liver synthetic failure, was established by fast atom bombardment ionization-mass spectrometry, which revealed elevated urinary bile acid excretion, a mass spectrum with intense ions at m/z 453 and m/z 510 corresponding to sulfate and glycosulfate conjugates of unsaturated monohydroxy-cholenoic acids, and an absence of primary bile acids. Gas chromatography-mass spectrometric analysis confirmed the major products of hepatic synthesis to be 3beta-hydroxy-5-cholenoic and 3beta-hydroxy-5-cholestenoic acids, which accounted for 96% of the total serum bile acids. Levels of 27-hydroxycholesterol were > 4,500 times normal. The biochemical findings were consistent with a deficiency in 7alpha-hydroxylation, leading to the accumulation of hepatotoxic unsaturated monohydroxy bile acids. Hepatic microsomal oxysterol 7alpha-hydroxylase activity was undetectable in the patient. Gene analysis revealed a cytosine to thymidine transition mutation in exon 5 that converts an arginine codon at position 388 to a stop codon. The truncated protein was inactive when expressed in 293 cells. These findings indicate the quantitative importance of the acidic pathway in early life in humans and define a further inborn error in bile acid synthesis as a metabolic cause of severe cholestatic liver disease.

Metabolic fate and hepatocyte toxicity of reverse amide analogs of conjugated ursodeoxycholate in the rat

Reverse amide analogs of conjugated bile acids were tested for their effects on the viability of cultured primary rat hepatocytes, for their transport and metabolism in the intact rat, and for their susceptibility to hydrolysis by intestinal bacteria. Succinylnorursodeoxycholanylamide (SNUDCN) and its parent C23 amine showed the same general lack of toxicity toward hepatocytes as the normal conjugates of ursodeoxycholic acid, at concentrations up to 500 microM. The 3alpha,7alpha,12alpha-trihydroxy analog and its parent amine were more toxic than the corresponding dihydroxy compounds, although their effects were similar to those observed for the normal conjugates of cholic acid. Following intraduodenal infusion, greater than 80% of administered SNUDCN appeared in the bile of bile fistula rats. Analysis of bile fractions indicated the presence of SNUDCN (81.5 mol% of original amount) and two metabolites, the taurine conjugate of SNUDCN (9.4 mol%) and SNUDCN containing an additional hydroxy group (9.1 mol%). Although SNUDCN underwent an efficient first pass enterohepatic circulation, it displayed a shorter biological half life than taurocholate (T1/2: 8.9 h vs 39.6 h, respectively). The reverse amide analogs were not hydrolyzed by any of a variety of intestinal bacteria known to hydrolyze normal conjugated bile acids. Despite the shorter half-life, the reverse amide analogs may be of potential use in the targeting of therapeutic bile acids to the colon.

Fetal and neonatal expression of the apical sodium-dependent bile acid transporter in the rat ileum and kidney

Previous investigations in rats older than 7 d have shown that apical sodium-dependent bile acid transport in the ileum is abruptly expressed at the time of weaning, whereas it is constitutively expressed in the kidney. The current study was designed to characterize the expression of sodium-dependent bile acid transport in late gestation and in the immediate postnatal period in the rat. Sodium-dependent bile acid transport was measured by rapid filtration using [3H]taurocholate and crude brush border membrane vesicles. Apical sodium-dependent bile acid transporter (ASBT) and ileal lipid binding protein (ILBP) expression were analyzed by Western and Northern blotting. Ileal bile acid content was measured by gas chromatography/mass spectrometry. In the ileum significantly greater sodium-dependent taurocholate uptake was measured in fetal d 22 (E22) membrane vesicles compared with postnatal d 7 (E22 17.0 +/- 5.7. P7 3.9 +/- 2.1 pmol/mg/60 s mean +/- SD, n = 3, p = 0.02). Gas chromatography/mass spectrometry revealed significant quantities of ileal bile acids at E22. Western and northern blotting of fetal ileum revealed ASBT but not ILBP. ASBT expression was suppressed by P7 and then reinduced by P21, whereas ILBP appeared to be first expressed postnatally. In contrast ASBT expression in the kidney was less age-dependent. Therefore, it appears that functional expression of the ASBT gene in the rat ileum is biphasic with a prenatal onset of expression, followed by repression in the early postnatal period and then marked reinduction at weaning.

Exposure of infants to phyto-oestrogens from soy-based infant formula

BACKGROUND

The isoflavones genistein, daidzein, and their glycosides, found in high concentrations in soybeans and soy-protein foods, may have beneficial effects in the prevention or treatment of many hormone-dependent diseases. Because these bioactive phyto-oestrogens possess a wide range of hormonal and non-hormonal activities, it has been suggested that adverse effects may occur in infants fed soy-based formulas.

METHODS

To evaluate the extent of infant exposure to phyto-oestrogens from soy formula, the isoflavone composition of 25 randomly selected samples from five major brands of commercially available soy-based infant formulas were analysed, and the plasma concentrations of genistein and daidzein, and the intestinally derived metabolite, equol, were compared in 4-month-old infants fed exclusively soy-based infant formula (n = 7), cow-milk formula (n = 7), or human breast-milk (n = 7).

FINDINGS

All of the soy formulas contained mainly glycosides of genistein and daidzein, and the total isoflavone content was similar among the five formulas analysed and was related to the proportion of soy isolate used in their manufacture. From the concentrations of isoflavones in these formulas (means 32-47 micrograms/mL), the typical daily volume of milk consumed, and average bodyweight, a 4-month-old infant fed soy formula would be exposed to 28-47 per day, or about 4.5-8.0 mg/kg bodyweight per day, of total isoflavones. Mean (SD) plasma concentrations of genistein and daidzein in the seven infants fed soy-based formulas were 684 (443) ng/mL and 295 (60) ng/mL, respectively, which was significantly greater (p < 0.05) than in the infants fed either cow-milk formulas (3.2 [0.7] and 2.1 [0.3] ng/mL), or human breast-milk (2.8 [0.7] and 1.4 [0.1] ng/mL), and an order of magnitude higher per bodyweight than typical plasma concentrations of adults consuming soy foods.

INTERPRETATION

The daily exposure of infants to isoflavones in soy infant-formulas is 6-11 fold higher on a bodyweight basis than the dose that has hormonal effects in adults consuming soy foods. Circulating concentrations of isoflavones in the seven infants fed soy-based formula were 13000-22000 times higher than plasma oestradiol concentrations in early life, and may be sufficient to exert biological effects, whereas the contribution of isoflavones from breast-milk and cow-milk is negligible.

Genetic and morphological findings in progressive familial intrahepatic cholestasis (Byler disease [PFIC-1] and Byler syndrome): evidence for heterogeneity

Byler disease (ByD) is an autosomal recessive disorder in which cholestasis of onset in infancy leads to hepatic fibrosis and death. Children who have a clinically similar disorder, but are not members of the Amish kindred in which ByD was described, are said to have Byler syndrome (ByS). Controversy exists as to whether ByD and ByS (subtypes of progressive familial intrahepatic cholestasis [PFIC]) represent one clinicopathological entity. The gene for ByD has been mapped to a 19-cM region of 18q21-q22. PFIC caused by a lesion in this region, including ByD, can be designated PFIC-1. Examination of haplotypes in siblings with ByS in two unrelated non-Amish families showed that the gene(s) responsible for their disorder(s) did not lie in the PFIC-1 candidate region. On light microscopy and transmission electron microscopy (TEM), liver tissue differed between Amish children with PFIC-1, who had coarsely granular bile and at presentation had bland intracanalicular cholestasis, and the children with ByS in the two non-Amish families, who had amorphous or finely filamentous bile and at presentation had neonatal hepatitis. Bile acid composition of bile also differed: In the Amish children with PFIC-1 and in one ByS family, the proportional concentration of chenodeoxycholic acid (CDCA) in bile was low compared with normal bile; in the other ByS family, it was only slightly reduced. Genetic analysis and light microscopy and TEM of liver may help distinguish PFIC-1 from other forms of ByS.

Ursodeoxycholate inhibits induction of NOS in human intestinal epithelial cells and in vivo

Ursodeoxycholate (UDCA) has anti-inflammatory and chemoprotective effects in animal models of inflammatory bowel disease and colon cancer. Because overproduction of nitric oxide (NO) by the inducible isoform of NO synthase (iNOS) is implicated in the pathogenesis of these conditions, we investigated the ability of UDCA to inhibit NO production in transformed human intestinal epithelial (DLD-1) cells. Nitrite/nitrate production was measured by the Griess reaction, enzymatic activity of iNOS was assessed by conversion of L-arginine to L-citrulline, and protein and mRNA were measured by Western and Northern blotting. Dose-dependent inhibition of interleukin-1 beta- and interferon-gamma-stimulated nitrite/nitrate production was observed when cells were preincubated for 6 h with UDCA (0-800 microM), and a substantial inhibition (81 +/- 3.2%) was seen at 500 microM. In cytokine-stimulated cells, UDCA reduced iNOS mRNA, protein, and enzyme activity without exerting cytotoxicity. UDCA had a minimal direct inhibitory effect on iNOS enzyme activity. UDCA pretreatment also reduced the expression of iNOS in the colonic epithelium of rats treated with bacterial lipopolysaccharide. Thus UDCA inhibits the induction of epithelial iNOS in vitro and in vivo, and this effect may contribute to the anti-inflammatory and chemoprotective actions of UDCA.

Hepatic basolateral sodium-dependent-bile acid transporter expression in two unusual cases of hypercholanemia and in extrahepatic biliary atresia

The recent cloning of a human sodium-dependent bile acid transporter (NTCP) permits analysis of its expression in human liver disease and investigation of potential primary defects in its expression. NTCP from normal human liver (NHL) was first characterized in detail. Northern blotting of RNA from NHL revealed a 1.8-kb NTCP transcript. Western blotting of crude NHL plasma membranes using a carboxyterminal antipeptide antibody showed that NTCP is a 39-kd polypeptide that is N-glycosylated to a final molecular weight of 56 kd. Indirect immunofluorescent analysis of NHL sections indicated that the NTCP protein is expressed on the basolateral surface of hepatocytes. We hypothesized that the clinical phenotype of a defect in NTCP might be hypercholanemia in the relative absence of liver disease. Accordingly, the coding region of the NTCP gene of two children with this phenotype was sequenced after reverse transcription/polymerase chain reaction (RT/PCR) amplification. No primary defects in the deduced NTCP amino acid sequence were found. Despite the extremely high serum bile salt levels (235 and 126 micromol/L) in these two patients, NTCP messenger RNA (mRNA) and protein expression were quantitatively normal, in contrast to the published observations in a rat model of cholestasis secondary to common bile duct ligation. Hepatic steady-state NTCP mRNA levels in a group of 23 pre- and postportoenterostomy biliary atresia patients were inversely related to total bilirubin, indicating that extrahepatic bile duct obstruction leads to down-regulation of NTCP mRNA levels, similar to that observed in rat common bile duct ligation. Therefore the lack of down-regulation in the two patients with hypercholanemia indicates that elevated serum bile salts are not sufficient to down-regulate NTCP expression, these two patients have abnormal responses to hypercholanemia, or these two patients have a defect in a gene other than NTCP that influences hepatic clearance of bile salts.

Effect of psyllium in hypercholesterolemia at two monounsaturated fatty acid intakes

We performed two studies to determine whether the lipid-lowering effect of viscous soluble fiber was modified by monounsaturated fatty acid (MUFA). First, psyllium (1.4 g/MJ) was compared with wheat bran (control) in 1-mo metabolic diets by using a randomized crossover design (n = 32 hyperlipidemic subjects). The background diet contained approximately 6% of energy as MUFA (20% of total fat). The second study (n = 27 hyperlipidemic subjects) was similar to the first but the background diet contained approximately 12% MUFA (29% of total fat) because of the addition of canola oil. At both fat intakes, psyllium resulted in significant reductions in total, low-density-lipoprotein (LDL), and high-density-lipoprotein (HDL) cholesterol compared with the wheat bran control. For the psyllium diet at 6% compared with 12% MUFA, the decreases in LDL cholesterol were 12.3 +/- 1.5% (P < 0.001) and 15.3 +/- 2.4% (P < 0.001), respectively. With the higher-MUFA diet triacylglycerol fell significantly over the control phase (16.6 +/- 5.5%, P = 0.006) and the ratio of LDL to HDL cholesterol fell significantly over the psyllium phase (7.3 +/- 2.8%, P = 0.015). Psyllium and MUFA intakes were negatively related to the percentage change in the ratio of LDL to HDL cholesterol (r = -0.34, P = 0.019 and r = -0.44, P = 0.002, respectively). Chenodeoxycholate synthesis rate increased (30 +/- 13%, P = 0.038) with the psyllium diet in the 12 subjects in whom this was assessed. We conclude that psyllium lowered LDL- and HDL-cholesterol concentrations similarly at both MUFA intakes. However, there may be some advantage in combining soluble fiber and MUFA to reduce the ratio of LDL to HDL cholesterol.

Additive hypocholesterolemic effect of psyllium and cholestyramine in the hamster: influence on fecal sterol and bile acid profiles

Recent findings suggest that the effects of cholestyramine and psyllium in combination could be additive for cholesterol-lowering. We therefore examined the effect of both agents, alone and in combination, on lipoprotein cholesterol and neutral and acidic steroid excretion in the hamster. Animals (n = 8/group) were fed for 21 days, either a basal chow diet supplemented with 10% palm oil and 0.2% cholesterol, or one of four treatments consisting of the basal diet plus: 5.5% cellulose; 5% psyllium with 0.5% cellulose; 0.5% cholestyramine with 5% cellulose; or 5% psyllium with 0.5% cholestyramine. Psyllium and cholestyramine both had significant hypocholesterolemic effects, but in combination produced additive reductions in lipoprotein and hepatic cholesterol. Psyllium, cholestyramine, and the combination increased total bile acid excretion by 26%, 57%, and 79%, respectively. Psyllium affected only unconjugated bile acid excretion while cholestyramine also increased the excretion of conjugated and primary bile acids. Neither agent, nor the combination, affected fecal neutral sterol excretion. We conclude that, while both agents lower cholesterol by a mechanism of increased bile acid excretion, these studies indicate that psyllium does not bind bile acids in vivo and lend further support for the concomitant use of these agents for cholesterol-lowering.

Bile acid concentrations in human and rat liver tissue and in hepatocyte nuclei

BACKGROUND & AIMS

Bile acids exert cellular and molecular effects in the liver, but little is known about tissue concentrations. The aim of this study was to characterize bile acid composition in human and rat liver tissue and hepatocyte nuclei and examine the effects of experimental cholestasis and bile acid administration.

METHODS

Bile acids were measured by gas chromatography-mass spectrometry.

RESULTS

Liver tissue concentrations of sham-operated rats were 130.8 +/- 21.3 nmol/g, representing 2%-4% of the bile acid pool; cholic and delta 22-beta-muricholic acids were the major bile acids identified. Concentrations increased 7-8-fold with bile duct ligation; deoxycholate and hyodeoxycholate disappeared. Lithocholate concentrations were higher in ligated rats (6.4 +/- 0.4 vs. 3.9 +/- 0.5 nmol/g for sham-operated). Total bile acid concentrations in human liver tissue were 61.6 +/- 29.7 nmol/g and comprised mainly chenodeoxycholic and cholic acids. Concentrations were higher during ursodeoxycholate or tauroursodeoxycholate administration (157.2 +/- 45.6 and 161.6 +/- 43.4 nmol/g, respectively), and liver tissue was enriched 30% in ursodeoxycholate at the expense of hydrophobic bile acids. Bile acids were identified in rat hepatic nuclei (50-110 pmol/4 x 10(7) nuclei), accounting for < 0.1% of liver tissue levels.

CONCLUSIONS

Human and rat liver tissue bile acid concentrations are low, increase with bile acid administration or bile duct ligation, and account for only a small fraction of the bile acid pool.

Byler-like familial cholestasis in an extended kindred

Progressive familial intrahepatic cholestasis (PFIC) occurs in many communities and races. A form of PFIC in five children from two consanguineous marriages in an Irish kindred is described. In addition, a review of clinical information from the records of three deceased members of the kindred strongly implies that they also suffered from PFIC. The children had a history of neonatal diarrhoea, sepsis, and intermittent jaundice that ultimately became permanent. They suffered intractable pruritus and growth retardation. Despite evidence of severe cholestasis, serum gamma-glutamyl transferase and cholesterol were normal in these children. Sweat sodium concentration were raised in three children. Liver histology showed severe intrahepatic cholestasis and hepatocellular injury. Urinary bile acid analysis revealed a non-specific pattern consistent with chronic cholestasis. These children suffer from a form of PFIC remarkably similar to that occurring in members of the Byler kindred.

Effect of ursodeoxycholic acid on hypertransaminasaemia and bile acid composition in patients undergoing bone marrow transplantation--a double-blind randomized control study

A double-blind randomized placebo controlled trial of ursodeoxycholic acid was performed in 31 patients undergoing T-cell depleted allogeneic or autologous bone marrow transplantation to determine the effectiveness of this hydrophilic bile acid in improving the increase in serum liver enzymes that generally accompanies this procedure. Neither group showed any significant difference in magnitude of the increases in serum transaminases and gamma-glutamyltranspeptidase following the conditioning regimen that included chemotherapy and total body irradiation. In the 6 months after transplantation, serum enzymes decreased in both groups, but were consistently higher in the placebo treated patients, indicating that ursodeoxycholic enhances normalization of liver. Faecal bile acid showed that following chemotherapy and irradiation in which intestinal bacteria are ablated, secondary bile acid formation was practically abolished and faeces contained mainly cholic and chenodeoxycholic acids. During bile acid treatment, ursodeoxycholic acid accounted for 31.3 +/- 10.9% of faecal bile acids compared with 4.0 +/- 2.1% in the basal period. Serum and urinary ursodeoxycholic acid concentrations (mean +/- SD, 13.3 +/- 6.9 mumol/L and 2.65 +/- 0.84 mumol/L, respectively) were significantly higher in patients receiving bile acid than in thos on placebo (mean +/- SD, 0.15 +/- 0.12 mumol/L and 0.29 +/- 0.35 mumol/L, respectively) thus confirming compliance.

Clinical pharmacokinetics of therapeutic bile acids

The pharmacokinetics of chenodeoxycholic and ursodeoxycholic acids are reviewed in this article. Chenodeoxycholic acid is well absorbed by the intestine, whereas the absorption of ursodeoxycholic acid is incomplete. They are extracted efficiently by the liver, conjugated with glycerine and taurine, secreted in bile, and then undergo enterohepatic circulation with the endogenous bile acids. Therapeutic bile acids are metabolised by intestinal bacteria to lithocholic acid which is mainly excreted with faeces. Since the large majority of bile acid is confined within the enterohepatic circulation (resulting in low serum concentrations) their volume of distribution is relatively high. Despite the high hepatic extraction, the clearance of therapeutic bile acids is relatively low because of the highly efficient enterohepatic recirculation. Elimination of therapeutic bile acids mainly occurs in the faeces either unmodified or after biotransformation. At present the main clinical indication for therapeutic bile acids is ursodeoxycholic acid treatment for chronic cholestatic liver disease. In these patients, ursodeoxycholic acid is efficiently absorbed but its hepatic uptake and biliary secretion are impaired, thus leading to reduced biliary enrichment and high serum concentrations of this exogenous bile acid. In patients with cystic fibrosis-associated liver disease, bile acid malabsorption also occurs, thus indicating the need for higher dosages. The volume of distribution and clearance of ursodeoxycholic acid reduced in the presence of liver disease. Also in this case, elimination mainly occurs with the faeces but, in the presence of severe cholestasis, renal clearance may become relevant. Sulphation or conjugation with glucose and N-acetylglucosamine facilitate urinary excretion.

Bile acid conjugation in early stage cholestatic liver disease before and during treatment with ursodeoxycholic acid

The efficiency of bile acid conjugation before and during therapy with 600 mg/day of ursodeoxycholic acid was measured in seven adult patients with early chronic cholestatic liver disease (6 with primary biliary cirrhosis; 1 with primary sclerosing cholangitis). Duodenal bile samples were obtained by aspiration and the proportion of unconjugated bile acids was determined using lipophilic anion exchange chromatography to separate bile acid classes, followed by analysis of individual bile acids by gas chromatography-mass spectrometry. The proportion of conjugated bile acids was determined by high-performance liquid chromatography. Use of a (99m)Tc-HIDA recovery marker permitted the absolute mass of unconjugated bile acids in the gallbladder to be calculated. Unconjugated bile acids comprised 0.4% of total biliary bile acids before and 0.2% during ursodeoxycholic acid therapy, indicating highly efficient conjugation of bile acids. During therapy, percentage unconjugated ursodeoxycholic acid significantly increased from (mean +/- S.D.) 13 +/- 13% to 54 +/- 12%; P < 0.002. When the unconjugated and conjugated fractions of bile acids were compared, there was an enrichment in unconjugated fraction for cholic acid and ursodeoxycholic acid and a depletion for chenodeoxycholic acid both in basal condition and during ursodeoxycholic acid therapy, suggesting that hydrophilic bile acids were conjugated less efficiently. During therapy, the conjugation efficiency significantly increased for cholic acid and ursodeoxycholic acid. The pretreatment mass of total unconjugated bile acids in the gallbladder was (mean +/- S.D.) 4.4 +/- 3.2 mumol, and was not significantly changed by ursodeoxycholic acid therapy (6.2 +/- 3.5 mumol). However, ursodeoxycholic acid therapy caused a significant increase in the mass of unconjugated ursodeoxycholic acid. It is concluded that endogenous bile acids and exogenous ursodeoxycholic acid when given at the usual dose are efficiently conjugated in patients with early cholestatic liver disease. Despite showing increased biliary unconjugated ursodeoxycholic acid during its oral administration, our data do not lend support to the occurrence of hypercholeresis due to cholehepatic shunting of bile acids.